Age: 81
Occupation: CEO, Berkshire Hathaway
As the world's third richest man, Buffett has long been influential. But now that the Oracle of Omaha has moved from reclusive investment tycoon to one of the President's informal economic advisers — with a very public and controversial stance on U.S. tax policy that would have him and his billionaire friends paying a lot more in taxes — he's certain to be an even bigger part of the nation's tax-reform conversation heading into the election.